Field of the Disclosure
The present invention relates to a tool changing method that changes a tool attached to a spindle of a machine tool with a next tool positioned at a standby position, and to a tool changer used therefor. More particularly, the present invention relates to a tool changing method and a tool changer which are capable of removing chips and the like adhering to the tools at the time of tool change.
Background of the Disclosure
In the field of machine tools having a tool changer, in changing a tool attached to a spindle, chips may adhere to a tapered portion of the tool, or the tool with chips adhering thereto may be stored into a tool magazine and then the chips may fall off the tool and adhere to tapered portions of other tools. It is known that there is a problem that, if such a tool with chips adhering to its tapered portion is attached to the spindle, the adhering chips cause the tool to be attached with an axis of the tool not aligned with an axis of the spindle or to be attached with the chips jammed between the tapered portion of the tool and the tapered hole of the spindle, and thereby the tool and the spindle are damaged; consequently, machining accuracy is reduced.
Accordingly, there has been proposed a tool changer and a method of preventing adhesion of chips to a tool or removing chips from a tool, as disclosed in Japanese Unexamined Patent Application Publication No. 2004-268177, which tool changer and method solve the above-mentioned problem by preventing adhesion of chips and the like to a tool or, if chips and the like adhere to a tool, removing them from the tool.
This conventional tool changer includes a tool magazine that holds a plurality of tools, and a tool change arm that has a gripper for gripping a tool and changes a tool attached to a spindle with one of the tools held by the tool magazine; the tool magazine includes holders that are disposed on a circumference of a circle having a center on a rotary shaft and hold the plurality of tools, a tool magazine drive motor that rotates the rotary shaft to index one of the tools held by the holders to a predetermined position, and other components. Further, the tool change arm can be rotated about a support shaft by a tool change arm drive motor, and is positioned by the tool change arm drive motor so that the gripper is positioned at a position facing the spindle or a position facing the indexed holder of the tool magazine. Note that operation of the tool magazine drive motor is controlled by tool magazine control means and operation of the tool change arm drive motor is controlled by tool change arm control means.
According to this tool changer, when a tool attached to the spindle is returned to the tool magazine, the tool change arm is positioned so that the gripper is positioned at the position facing the spindle, and the tool is gripped by the gripper and detached from the spindle. Thereafter, the tool change arm is positioned so that the gripper is positioned at the position facing a holder indexed at the predetermined position, and the tool gripped by the gripper is transferred to the holder. Further, when a tool held by the holder is attached to the spindle, the tool change arm is positioned so that the gripper is positioned at the position facing the indexed holder, and the tool held by the holder is gripped by the gripper and detached from the holder. Thereafter, the tool change arm is positioned so that the gripper is positioned at the position facing the spindle, and the tool gripped by the gripper is attached to the spindle.
The tool magazine control means in this tool changer is configured not only to control the operation of indexing one of the holders of the tool magazine to the predetermined position but also to control an operation of repeating normal rotation and reverse rotation of the tool magazine drive motor with a predetermined period or repeating rotation and stopping of the tool magazine drive motor with a predetermined period, whereby the tool magazine is vibrated and chips adhering to the tools are removed by the vibration.
Further, the tool change arm control means is configured not only to control the operation of positioning the tool change arm so that the gripper is positioned at the position facing the spindle or the position facing the holder of the tool magazine but also, similarly to the above, to control an operation of repeating normal rotation and reverse rotation of the tool change arm drive motor with a predetermined period or repeating rotation and stopping of the tool change arm drive motor with a predetermined period, whereby the tool change arm is vibrated and chips are removed from the tool.